Is this the beginning of the end for firefox?

I began using firefox in late 2003. I was drawn to the browsers incredible security, speed, and efficient use of system of system resources. up untill version 1.06, each release had been equally as stable and lean as the last. 1.06 and .07 seemed just a bit slower, but still very tolerable. After installing and using 1.5 for a month, i just want to wonder, what happened? The browser chews through memory, somtimes using 30% CPU cycles. The browser has managed to crash my PC, which us based on an athlon 64 3200+ and 1 gig of ram. The browser also crashes during more page loads than any other version that I have ever used. i don't know if its just sloppy coding, or a beta that was pushed out too soon as a final release. At this point it seems to me that it takes up as much memory as IE, if not more, not to mention the huge memory leak that grows of browser is left open for more than 12 hours. I really hope that the Mozilla dev team will work these problem out. The last few versions of the browser were perfect, why ruin the record now?